1. The Field of the Invention
The invention concerns a cell culture harvesting device with a scraper head having a blade with a cutting edge and a guide strip to move the scraper head.
2. Related Applications
Foreign priority benefits under Section 119 of Title 35 of the United States Code of German Utility Model Application No. 196 44 761.5, filed Oct. 29, 1996, incorporated herein by reference, are claimed for this application.
3. The Relevant Technology
Cell culture harvesting devices in the form of scrapers which have a scraper head and a rod-shaped stem, which is sometimes also withdrawable, are well-known and common laboratory equipment. Typically, the dimensions of the scraper head are adapted to the neck openings of common cell culture flasks, since it must be introduced into the cell culture vessel through this opening. Cultured cells grow and adhere to the curved wall of roller bottle-type cell culture vessels and to the flat-surfaced wall forming the floor in cell culture vessels having relatively flat parallel walls. For purposes of this disclosure, the term "floor" is used to refer to the growth surface of a cell culture vessel, i.e., the curved wall of roller bottle-type cell culture vessels or the flat-surfaced floor wall of other types of cell culture vessels, where cells grow and adhere and from which such cells need to be harvested, i.e., removed, by the cell culture harvesting devices in accord with the present invention as disclosed herein. Accordingly, conventional cell culture harvesting devices operate to lift the adherent cells on the floor of the cell culture vessel off the surface of the floor by the scraper head which is moved by the guide strip.
For example, cell culture scrapers of this kind are described in the 1995-1996 laboratory catalog of the company Nunc GmbH under the numbers 179693 and 179707, and in the catalog of the company Baxter Diagnostics, Inc., Scientific Products Division under the numbers T4206-1, T4130-56, 57, 58, T4136-36, 37, and T4160-157. In some cases, the scraper head can be rotated with respect to the guide strip, so that a greater area of cell culture growth surface can be reached.
Cell removal devices for removing multiple cell cultures are also known from U.S. Pat. No. 4,004,981. The devices are utilized with cylindrical cell culture vessels having a number of circular cell culture growth surfaces stacked at a distance on top of one another parallel to the cylindrical front surfaces. The cell culture scraper has at least one scraper head which is circular in cross section and which is placed onto the circular cell culture growth surfaces. Rotating motions of the cell culture scraper and/or the cell culture growth surfaces effects lifting of the cells off the growth surface or pushing of the cells to the edge of the growth surface. If the cell culture scraper has several scraper heads, then several cell culture growth surfaces can be processed/harvested simultaneously.
A problem encountered during cell culturing is the risk of contamination of the cells and/or the cell culture vessel during the process. To reduce the risk of contamination by introduction of cell culture scrapers of the previously described type into the cell culture vessel, it is necessary to use sterile scrapers. Therefore, some of these scrapers are offered already sterilized in individual packages, while others must be sterilized before use in a separate sterilization process. Introducing the scraper into the cell culture vessel and placing it onto the cell culture growth surface requires careful and precise handling on the part of the operating personnel, since otherwise the cells can easily be mechanically damaged or even destroyed due to insufficient care and attention. Especially with roller bottle-type cell culture vessels, cell culture harvesting with known cell culture scrapers is relatively ineffective because reaching all areas of the growth surface is technically very difficult and/or depends too much on the skill, care, and attention of operating personnel. Another problem with conventional cell scraper devices is seen in the fact that, depending on the scraper head's angle of attack, the cells which are lifted can accumulate in front of or behind the scraper head in such a way that the cells are distorted and/or damaged in the process.
Moreover, cell culture harvesting procedures are known which lift the adherent cells from the growth surface of the cell culture vessel by adding chemical loosening fluids. Typically, knocking or vibrating the growth surface is used to promote this process. U.S. Pat. No. 4,556,639 describes such a cell culture harvesting procedure and a device suitable for implementation thereof. According to this procedure, the cell culture is first placed in a flat cell culture vessel and is subjected to the action of an enzyme-containing solution which reduces the adhesion of the cells to the growth surface of the cell culture vessel. Next, the cell culture vessel is placed into the receptacle of an apparatus which effects movement of the prepared cell culture growth surface in the perpendicular and/or parallel direction to the growing surface. The movement can be produced by ultrasound. The receptacle with the cell culture vessel is also moved parallel to the plane of the growth surface in a direction which is opposite to the movement already described. Due to the actions of the enzyme solution and the multiple-direction movements of the cell culture vessel, the cells are dislodged such that these can be suitably removed and spatially concentrated by withdrawing the enzyme-containing solution containing the cells from the cell culture vessel. Manipulation according to the procedure described is labor-intensive and requires the special apparatus. In addition, the procedure is not very flexible due to the combination of chemical and physical methods.
Therefore, it is the task of the invention to eliminate the disadvantages encountered with conventional cell culture harvesting apparatus and methods. In particular, it would be an advancement to provide cell culture harvesting devices that are simple, cost-effective, and versatile and which minimize the risk of contamination and the potential for distorting and/or damaging cultured cells during the harvesting process.